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CN-119040988-B - Preparation method of fluorine corrosion resistant micro-arc oxidation coating on aluminum alloy surface

CN119040988BCN 119040988 BCN119040988 BCN 119040988BCN-119040988-B

Abstract

A method for preparing fluorine corrosion resistant micro-arc oxidation coating on aluminum alloy surface comprises the following steps of forming a passivation film on the surface of an aluminum alloy substrate, washing and drying, and forming fluorine corrosion resistant micro-arc oxidation coating on the surface of the passivation film. The method adopts a two-step micro-arc oxidation method, wherein a passivation film is formed on the surface of an aluminum alloy by the first-step micro-arc oxidation, the micro-arc oxidation failure caused by incapability of starting an arc in high-conductivity doped Y 3+ electrolyte is avoided through the passivation film, and the second-step micro-arc oxidation is performed by doping Y 3+ in the electrolyte so as to influence the plasma discharge efficiency of the coating, reduce the formation of oxygen vacancies of the coating, form more stable electron and ion transmission discharge channels, improve the surface compactness of the MAO coating, reduce defect cracks, change the surface structure of MAO aluminum oxide by yttrium doping, and have higher mismatch degree and interface stability of corrosion products, thereby improving the corrosion resistance of the MAO coating in a fluorine environment and having good wear resistance.

Inventors

  • XIAO SHU
  • YE ZISHUO
  • ZHAO SHENG
  • ZHANG HU
  • JIANG SAIHUA

Assignees

  • 华南理工大学

Dates

Publication Date
20260512
Application Date
20240910

Claims (6)

  1. 1. The preparation method of the fluorine corrosion resistant micro-arc oxidation coating on the surface of the aluminum alloy is characterized by comprising the following steps: Step S10, connecting the polished and dried aluminum alloy matrix with a primary micro-arc oxidation power supply anode, and placing the aluminum alloy matrix in a primary electrolyte for primary micro-arc oxidation to form a passivation film on the surface of the aluminum alloy matrix, wherein the primary electrolyte is sodium hexametaphosphate, sodium silicate and deionized water, the concentration of the sodium hexametaphosphate is 20-40g/L, the concentration of the sodium silicate is 2-8g/L, the primary micro-arc oxidation time is 1-4min, and the thickness of the passivation film is 0.1-2 mu m; Step S11, washing an aluminum alloy matrix containing a passivation film by deionized water, and then drying at room temperature; And S12, connecting the dried aluminum alloy matrix containing the passivation film with a secondary micro-arc oxidation power supply anode, and placing the aluminum alloy matrix in a secondary electrolyte for secondary micro-arc oxidation to form a fluorine corrosion resistant micro-arc oxidation coating on the surface of the passivation film, wherein the secondary electrolyte comprises sodium hexametaphosphate, sodium silicate, yttrium nitrate and deionized water, the concentration of the sodium hexametaphosphate is 25-40g/L, the concentration of the sodium silicate is 2-10g/L, the concentration of the yttrium nitrate is 1-5mol%/L, the second micro-arc oxidation time is 6-10min, and the thickness of the fluorine corrosion resistant micro-arc oxidation coating is 5-25 mu m.
  2. 2. The method for preparing a fluorine corrosion resistant micro-arc oxidation coating on an aluminum alloy surface according to claim 1, wherein in step S10, a constant current mode is adopted for the first micro-arc oxidation, the frequency is 400-800Hz, the positive and negative duty ratio is 10-30%, and the current density is 0.1-2A/dm 2 .
  3. 3. The method for producing a fluorine corrosion resistant micro-arc oxidation coating on an aluminum alloy surface according to claim 1, wherein the rinsing time is 1-5min in step S11.
  4. 4. The method for preparing a fluorine corrosion resistant micro-arc oxidation coating on an aluminum alloy surface according to claim 1, wherein in step S12, the second micro-arc oxidation is performed in a constant current mode, the frequency is 400-800Hz, the positive and negative duty ratio is 10-30%, and the current density is 0.1-2A/dm 2 .
  5. 5. The method for producing a fluorine corrosion resistant micro-arc oxidation coating according to any one of claims 1 to 4, wherein the primary electrolyte and the secondary electrolyte are maintained at a temperature of 20 to 50 ℃ during the micro-arc oxidation.
  6. 6. The method for producing a fluorine corrosion resistant micro-arc oxidation coating on an aluminum alloy surface according to any one of claims 1 to 4, wherein in step S10, the polishing method comprises: under a water cooling environment, sequentially adopting SiC sand paper with 800, 1200, 2000 and 3000 meshes to polish the surface of an aluminum alloy matrix; And (3) secondarily polishing the surface of the aluminum alloy matrix by using flannelette coated with the polishing paste.

Description

Preparation method of fluorine corrosion resistant micro-arc oxidation coating on aluminum alloy surface Technical Field The invention relates to the technical field of material surface treatment, in particular to a preparation method of a fluorine corrosion resistant micro-arc oxidation coating on an aluminum alloy surface. Background Aluminum alloys have high demands in the field of semiconductor devices due to their high strength to weight ratio, good wear resistance and corrosion resistance, and excellent workability. Highly corrosive fluorine-containing compounds are often used in semiconductor manufacturing processes, greatly affecting the useful life of aluminum alloys. The micro-arc oxidation (MAO) technology can form a layer of micro-arc oxidation coating (ceramic protective oxide film) with excellent performance on the metal surface in situ, and is one of effective means for improving the corrosion resistance of aluminum alloy. However, due to the unstable discharge of the micro-arc oxidation technology, the micro-arc oxidation coating inevitably forms micro-holes and micro-cracks, and fluorine has strong electronegativity, so that embrittled ionic crystal fluoride is easy to form after the coating is corroded, and the corrosion resistance and the wear resistance of the micro-arc oxidation coating are poor under the fluorine environment. Disclosure of Invention Based on the above, the invention aims to provide a preparation method of a fluorine corrosion-resistant micro-arc oxidation coating on the surface of an aluminum alloy, so as to improve the corrosion resistance and the wear resistance of the micro-arc oxidation coating. A preparation method of a fluorine corrosion resistant micro-arc oxidation coating on the surface of an aluminum alloy comprises the following steps: step S10, connecting the polished and dried aluminum alloy matrix with a primary micro-arc oxidation power supply anode, and placing the aluminum alloy matrix in a primary electrolyte for primary micro-arc oxidation to form a passivation film on the surface of the aluminum alloy matrix, wherein the primary electrolyte comprises sodium hexametaphosphate, sodium silicate and deionized water; Step S11, washing an aluminum alloy matrix containing a passivation film by deionized water, and then drying at room temperature; And S12, connecting the dried aluminum alloy matrix containing the passivation film with the anode of a secondary micro-arc oxidation power supply, and placing the aluminum alloy matrix in a secondary electrolyte for secondary micro-arc oxidation to form a fluorine corrosion resistant micro-arc oxidation coating on the surface of the passivation film, wherein the secondary electrolyte comprises sodium hexametaphosphate, sodium silicate, yttrium nitrate and deionized water. Further, in step S10, the concentration of the sodium hexametaphosphate is 20-40g/L, and the concentration of the sodium silicate is 2-8g/L. Further, in step S10, the first micro-arc oxidation adopts a constant current mode, the frequency is 400-800Hz, the positive and negative duty ratio is 10-30%, and the current density is 0.1-2A/dm 2. Further, in step S10, the first micro-arc oxidation time is 1-4min, and the thickness of the passivation film is 0.1-2 μm. Further, in step S11, the rinsing time is 1-5min. Further, in step S12, the concentration of sodium hexametaphosphate is 25-40g/L, the concentration of sodium silicate is 2-10g/L, and the concentration of yttrium nitrate is 1-5mol%/L. Further, in step S12, the second micro-arc oxidation adopts a constant current mode, the frequency is 400-800Hz, the positive and negative duty ratio is 10-30%, and the current density is 0.1-2A/dm 2. Further, in step S12, the second micro-arc oxidation time is 6-10min, and the thickness of the fluorine corrosion resistant micro-arc oxidation coating is 5-25 μm. Further, during the micro-arc oxidation, the temperature of the primary electrolyte and the secondary electrolyte is maintained at 20-50 ℃. Further, in step S10, the polishing method includes: under a water cooling environment, sequentially adopting SiC sand paper with 800, 1200, 2000 and 3000 meshes to polish the surface of an aluminum alloy matrix; And (3) secondarily polishing the surface of the aluminum alloy matrix by using flannelette coated with the polishing paste. Compared with the prior art, the method adopts a two-step micro-arc oxidation method, wherein a passivation film is formed on the surface of the aluminum alloy by the first-step micro-arc oxidation, so that micro-arc oxidation failure caused by incapability of starting an arc in high-conductivity doped Y 3+ electrolyte is avoided through the passivation film, and the second-step micro-arc oxidation is performed by doping Y 3+ in the electrolyte so as to influence the plasma discharge efficiency of the coating, reduce the formation of oxygen vacancies of the coating, form more stable electron and ion transmission discharge channels, i